1. Field of the Invention
The invention relates to a heat-insulating structure and, more particularly, to an injection molding machine and a heat-insulating structure of a barrel thereof.
2. Description of the Related Art
In plastic manufacturing industry, injection molding is the most common manufacturing method. Generally, plastic is mixed and melted, and then the plastic is pressed and injected into a mold via a barrel.
The barrel is a main heat generating region in an injection molding machine, and a surface temperature of the barrel generally can reach 200° F. However, in a conventional injection molding machine, the barrel is exposed to an operation environment. Therefore, heat generated from the barrel by heat radiation directly dissipates into the operation environment, thereby causing a high temperature of an operation region of the injection molding machine and worsening the operation environment of operators. Further, if the injection molding machine is disposed in a room having an air conditioner, the load of the air conditioner greatly increases, thereby increasing power consumption.
In addition, to obtain plastic injection products with good quality, the temperature, pressure, and flow speed in the process of pressing and injecting the molten plastic need to be well controlled. However, since the barrel is exposed to the operation environment, the temperature of the operation environment has a great effect on the temperature of the molten plastic. In detail, if the temperature of the operation environment is lower, the temperature of the molten plastic decreases, the viscosity of the plastic increases, and the flow speed decreases. Further, as the flow speed decreases, the temperature of the molten plastic decreases, thereby causing a vicious circle. If the temperature of the operation environment is higher, the temperature of the molten plastic decreases less, the viscosity of the plastic increases less, and the flow speed increases. Further, as the flow speed increases, the temperature of the molten plastic decreases less, and the flow speed increases, thereby also causing a vicious circle. Thus, the quality of the injection products is greatly affected.